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Journal Article

Low-Order Contact Load Distribution Model for Ball Nut Assemblies

2016-04-05
2016-01-1565
Ball nut assemblies (BNAs) are used in a variety of applications, e.g., automotive, aerospace and manufacturing, for converting rotary motion to linear motion (or vice versa). In these application areas, accurate characterization of the dynamics of BNAs using low-order models is very useful for performance simulation and analyses. Existing low-order contact load models of BNAs are inadequate, partly because they only consider the axial deformations of the screw and nut. This paper presents a low-order load distribution model for BNAs which considers the axial, torsional and lateral deformations of the screw and nut. The screw and nut are modeled as finite element beams, while Hertzian Contact Theory is used to model the contact condition between the balls and raceways of the screw and nut. The interactions between the forces and displacements of the screw and nut and those at the ball-raceway contact points are established using transformation matrices.
Journal Article

Development of Fracture Model for Laser Screw Welding

2016-04-05
2016-01-1344
This paper describes the development of a fracture finite element (FE) model for laser screw welding (LSW) and validation of the model with experimental results. LSW was developed and introduced to production vehicles by Toyota Motor Corporation in 2013. LSW offers superb advantages such as increased productivity and short pitch welding. Although the authors had previously developed fracture FE models for conventional resistance spot welding (RSW), a fracture model for LSW has not been developed. To develop this fracture model, many comprehensive experiments were conducted. The results revealed that LSW had twice as many variations in fracture modes compared to RSW. Moreover, fracture mode bifurcations were also found to result from differences in clearance between welded plates. In order to analyze LSW fracture phenomena, detailed FE models using fine hexahedral elements were developed.
Journal Article

Compression Behavior of DIN C10C and SAE-AISI 1010 Steels During Riveting of Clutch Disc Spacer Bolts: Experimental and Computational Analysis

2017-03-28
2017-01-0224
The rapid growth of the emerging markets has pushed the automotive original equipment manufacturers to relocalize production to reduce manufacturing and logistic costs. To ensure an efficient and flexible supply chain, local suppliers are appointed. However, the characteristics of materials available in each region may have minor differences, and when geometry and process design recommendations that were developed for certain materials are implemented for materials under a different regional standard, different results are obtained. Such is the case of the clutch disc spacer bolt, in which its compression during riveting has a direct effect in the noise and vibration isolation of the vehicle. It has been reported that spacer bolts produced with materials considered to be equivalent in Europe and North America (DIN C10C and SAE-AISI 1010 steels) behave different during riveting, even though they have very similar chemical compositions and are delivered with a similar UTS and ductility.
Technical Paper

Avoiding Safety Scandals by Controlling the Risk of Material Changes

2017-03-28
2017-01-0373
Achieving functional safety in mechatronic systems with growing product functionality is a major challenge in systems engineering. Following the current discussion, this challenge is mostly allocated to electronics and software development. For most of the scenarios this focus is feasible. Product design - the construction of the product - defines the properties and the appearance of the product by shape, material and assembly. So, the product design is often not under control of the safety management system. A hazardous deviation of part shape can be easily identified after the parts product or at least at its mounting. A wrong assembly is controlled by assembly documentation or data (e.g. screw torques) and identified at end of assembly line checks. The identification of a hazardous material choice depends on the product material class. Product materials can be separated into two classes: passive or active materials.
Journal Article

The Effect of Outer Ring Flange Concavity on Automotive Wheel Bearings Performance

2016-09-18
2016-01-1976
Through transmitting power and carrying vehicle weight, automotive wheel bearings play an important role. Counterbalancing the bearing responsibilities, they also are designed to last the life of a vehicle without servicing. When mounted to the vehicle steering knuckle by bolts, distortion occurs to the outer ring. Performance is affected when distortion takes place at the seal mounting location and raceways. Finite element analysis using commercial software was performed to analyze the outer ring distortion. Elasto-plastic and contact analyses were carried out to compute the clamping behavior of the outer ring, bolts and the knuckle under various conditions. To verify the reliability of this study, the distortion of the outer ring was measured. The experimental results proved to be comparative with the analysis results.
Technical Paper

High Flushness Installation of Countersunk Fasteners

2016-09-27
2016-01-2112
Aerospace structures are typically joined to form larger assemblies using screw lock or swage lock fasteners or rivets. Countersunk fasteners are used widely in the aerospace industry on flying surfaces to reduce excrescence drag and increase aircraft performance. These fasteners are typically installed to a nominal countersink value which leaves them flush to the surface before being locked into position. The Northern Ireland Technology Centre (NITC) at Queen’s University Belfast has developed and demonstrated two processes which enable high tolerance flush fastening of countersunk fasteners: The ‘Flush Install’ process produces countersunk holes based on the specific geometry of each individual fastener; The ‘Fettle Flush’ process accurately machines fasteners to match the surrounding surface. Flushness values well within the allowable tolerances have been demonstrated for both Flush Install and Fettle Flush processes.
Technical Paper

Ting Noise Generation in Automotive Applications

2017-03-28
2017-01-1121
Automobile customers are looking for higher performance and quieter comfortable rides. The driveline of a vehicle can be a substantial source of NVH issues. This paper provides an understanding of a driveline noise issue which can affect any variant of driveline architecture (FWD, AWD, RWD and 4X4). This metallic noise is mostly present during the take-off and appropriately termed as ting noise. This noise was not prevalent in the past. For higher fuel economy, OEMs started integrating several components for lighter subsystems. This in effect made the system more sensitive to the excitation. At present the issue is addressed by adding a ting washer in the interface of the wheel hub bearings and the halfshafts. This paper explains the physics behind the excitation and defines the parameters that influence the excitation. The halfshaft and the wheel hub are assembled with a specified hub nut torque.
Technical Paper

The Design and Evaluation of EMB Actuator Scheme

2017-09-17
2017-01-2508
Electromechanical Braking System (EMB) stops the wheel by motor and related enforce mechanism to drive braking pads to clamp the friction plate. It is compact in sized as well as faster in response, which solves the issue of potential leakage and slows response of traditional hydraulic brake system. The institutions at home and abroad have put forward all kinds of new structural schemes of EMB. At present, there are various EMB structural schemes, but the analysis and evaluation of these schemes are relatively few. In this paper, on the basis of a large number of research, the EMB actuator is modular decomposed according to function ,then the parametric 3D model library of each function module is established. According to brake requirements of the target vehicle, a development platform is set up to match EMB actuator structure scheme quickly.
Journal Article

Development of Axial Force Testing System for Wheel Bearing

2017-09-17
2017-01-2522
The actual installed conditions of 1st, 2nd and 3rd generation of wheel bearing were introduced. The theoretical factors of the axial fastening force for the axle (or CVJ bolts) and nuts were analyzed and the requirements for building up a precise axial force test system were given out. Four testing plans were discussed for the requirements. Based on the cases, the axial force test system was built up, and the axial force test was successfully carried out for the front wheel bearing of a car.
Journal Article

Condition Monitoring of Multi-Bolted Joints with Combination of Preload Measurement and Extended Evaluation from FEA

2017-01-10
2017-26-0308
This paper shows an approach developed to cover in detail different behaviour of threaded fasteners with a robust test setup for multibolted joints and numerical simulations by means of finite element analysis (FEA). Resulting from this combination, it is possible to monitor the axial, torsion and bending stress in fasteners themselves. Importance is given to interpretation of the measurement signals of strain gauge bolts. Integrity of the complete structure can be better interpreted with this approach. This depends on the modelling of bolts for FEA and the quality of the measured signals from experiments. For FE modelling the general purpose non-linear solver Abaqus is used, for preload measurement strain gauges are integrated into metric bolts. Simulation and experimental results from this unique test setup with several bolts are shown.
Technical Paper

Methodology for Determination and Optimization of Bolted Joints

2017-11-07
2017-36-0294
In order to optimize the development of bolted joints used to components attachments in the Sidemember of commercial vehicles, the joints development has become relevant to better definition of the fasteners size, eliminating overweight and avoiding under or super-sized. This paper presents a development sequential approach of bolted joints applied on commercial vehicles ensuring the correct specifications usage of the fasteners and the joint to keep their clamp force. The evaluations were conducted based on theoretical and practical aspects applied on products and in the definition of all elements contained in a joint. The calculation methodology was developed based on standardized bolts and forces generated through the reactions of the components required for each vehicle family.
Technical Paper

Improve Frame Assembly Flexibility with Low Investment

2017-11-07
2017-36-0132
Commercial vehicles are being developed for long decades in Brazil creating a deep background on manufacturing process. With the current scenario a variety of different vehicles specifications (weight capacity, load distribution, torque, size, etc.) are being required by the market. Joints with bolts and nuts are the engineering solution for the most of the problems found in automotive engineering regarding commercial vehicles. Screw processes were made during the last 150 years. Nowadays current frame modifications on aftermarket are made with arc weld process that affects directly the material properties and the process needs to be performed by critical personal with training and capacity. In addition cost and timing does not fit for the best equation on how to proceed with the modifications. The solution proposed brings more flexibility on frame assemblies that can be extended to other products.
Technical Paper

Structural and Cost Evaluation of Snap Fits used in Connections of Vehicle Door Trim Panel Components with FEA Assist

2017-11-07
2017-36-0195
Among the most important finishing structures of a vehicle interior, the door trim panels reduce external noises, present ergonomic concepts generating comfort, improve appearance, and provide objects storage, knobs and buttons. The panels usually composed of several molded parts (trim, armrest, etc.) connected to each other also have structural function as support closing loads, protect occupants of door internal mechanisms, energy absorption in side impacts and resist misuse conditions. Therefore, these trims usually made of polymeric materials must to present good structural integrity, demanding appropriate connections between components to have good load distribution. The connections between parts can be made using bolts, interference fits (like self-locking), welding tubular plastic towers (heat stakes), or clips (such as snap fits) and last two are the most common due to be cheap and with good retention.
Technical Paper

Development of friction coefficient controller for E-coat (KTL)

2018-09-03
2018-36-0224
Global competitiveness increase in the past decades has been a crucial factor for the technological advance and industrial automotive development. Possibility of reducing costs, concentrate knowledge and increase in manufacturing efficiency has lead to development of global automotive platforms. In this scenario, the supply chain needs for adaptations that allow evolution at the same fastness imposed by original equipment manufacturer (OEM). Such demands reflect directly on the fasters market requiring lighter and stronger products. Stronger products are obtained by increasing corrosion resistance and lowering friction coefficient, in order to increase the clamp load and, consequently, reduce the weight without reducing performance. However, increasing corrosion resistance causes, generally, an increase in friction coefficient and, consequently, a decrease in clamp load.
Technical Paper

Steering Feedback Perception of Average Drivers

2018-04-15
2018-01-5014
Electromechanical steering systems (EPS) provide assisting steering force through an electric motor, often paired with a screw drive. The combination of an electric motor and a screw drive lead to high inertia and thus to a reduced feedback of tire force behavior at the steering wheel. This force behavior contains information about driving conditions and road surface. However, the electric motor can be used to actively enhance and manipulate steering feedback. This article describes the driver perception of modified steering feedback. The presented data is collected carrying out a driving simulator study with average drivers as test subjects. In this study the driver experiences a modified steering feedback at a change of road friction coefficient. Based on the test subjects ratings the perception, acceptance and controllability of the presented steering feedback modifications are assessed.
Technical Paper

Design Influences on Self-loosening Behaviour of Multi-bolted Joint

2018-04-03
2018-01-1231
Most studies on self-loosening behaviour of bolted joints under relative transverse movement of the clamped parts are limited to a single bolt joint. In this paper a comprehensive assessment is performed for the loosening behaviour of a multi-bolted joint with two bolts. Design influences such as material of clamped part and geometrical distance between bolts are investigated experimentally and using three dimensional finite element analysis. The importance of studying the component influence on self-loosening behaviour is highlighted using different cross sections of the clamped part. Influence of component deformation behaviour on self-loosening behaviour of the bolts are illustrated by experimental and simulation results. Risks of decomposing a multi-bolted joint into a single bolt joint for experimental investigation, such as in Junker’s test are highlighted.
Journal Article

Failure Mode and Fatigue Behavior of Flow Drill Screw Joints in Lap-Shear Specimens of Aluminum 6082-T6 Sheets Made with Different Processing Conditions

2018-04-03
2018-01-1237
Failure mode and fatigue behavior of flow drill screw (FDS) joints in lap-shear specimens of aluminum 6082-T6 sheets made with different processing conditions are investigated based on the experimental results and a structural stress fatigue life estimation model. Lap-shear specimens with FDS joints without clearance hole and lap-shear specimens with stripped FDS joints with clearance hole were made and then tested under quasi-static and cyclic loading conditions. Optical micrographs show the failure modes of the FDS joints without clearance hole (with gap) and the stripped FDS joints with clearance hole under quasi-static and cyclic loading conditions. The fatigue failure mode of the FDS joints without clearance hole (with gap) in lap-shear specimens is similar to those with clearance hole. The fatigue lives of lap-shear specimens with FDS joints without clearance hole are lower than those with clearance hole for given load ranges under cyclic loading conditions.
Journal Article

Failure Mode and Fatigue Behavior of Flow Drill Screw Joints in Lap-Shear Specimens of Aluminum 6082-T6 Sheets of Different Thicknesses

2018-04-03
2018-01-1239
Failure mode and fatigue behavior of flow drill screw (FDS) joints in lap-shear specimens of aluminum 6082-T6 sheets of different thicknesses are investigated based on the experimental results and a structural stress fatigue life estimation model. Lap-shear specimens of different thicknesses with FDS joints with clearance hole were made and tested under quasi-static and cyclic loading conditions. Optical micrographs show the failure modes of the FDS joints with clearance hole in lap-shear specimens of different thicknesses under quasi-static loading conditions. Under quasi-static loading conditions, as the thickness increases, the FDS joint failed from the penetration of the screw head into the upper sheet to the failure of the screw between the two sheets. Optical micrographs also show the failure modes of the FDS joints with clearance hole in lap-shear specimens of different thicknesses under cyclic loading conditions.
Technical Paper

Hydrogen Embrittlement Susceptibility of Case Hardened Steel Fasteners

2018-04-03
2018-01-1240
This work establishes the relationship between core hardness, case hardness, and case depth on susceptibility to hydrogen embrittlement of case hardened steel fasteners. Such fasteners have a high surface hardness in order to create their own threads in a mating hole, and are commonly used to attach bracketry and sheet metal in automotive applications. While case hardened fasteners have been studied previously, there are currently no processing guidelines supported by quantitative data for fastener standards. Through sustained load embrittlement testing techniques, the susceptibility of case hardened steel tapping screws to internal and environmental hydrogen embrittlement is examined. Further characterization of the fastener samples through microhardness testing, microstructure review, and fracture surface examination allows the investigation of susceptibility thresholds. It is shown that core hardness is the primary consideration for susceptibility.
Technical Paper

Modified Experimental Approach to Investigate Coefficient of Friction and Wear under Lubricated Fretting Condition by Utilizing SRV Test Machine

2018-04-03
2018-01-0835
Fretting is an important phenomenon that happens in many mechanical parts. It is the main reason in deadly failures in automobiles, airliners, and turbine engines. The damage is noticed between two surfaces clamped together by bolts or rivets that are nominally at rest, but have a small amplitude oscillation because of vibration or local cyclic loading. Fretting damage can be divided into two types. The first type is the fretting fatigue damage where a crack would initiate and propagate at specific location at the interface of the mating surfaces. Cracks usually initiate in the material with lower strength because of the local cyclic loading conditions which eventually lead to full failure. The second type is the fretting wear damage because of external vibration. Researchers have investigated this phenomenon by theoretical modeling and experimental approaches. Although a lot of research has been done on fretting damage, some of the parameters have not been well studied.
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